Many catheter devices have been designed and patented which can be passed through an orifice of a patient to obtain a culture specimen or tissue sample internally by aspiration or similar method without the necessity of surgical incision. These catheters may be endotracheal catheters, urethral catheters, trocar catheters, or the like, which are employed for withdrawing fluid or tissue from the patient. While not limiting the invention herein, the device disclosed is of a type suitable for obtaining tracheal or sputum specimens from the lower respiratory tract free of contamination from oral, nasal and/or pharyngeal secretions. It should be readily apparent that uncontaminated sampling facilitates accurate diagnosis.
One type of catheter device is shown in Linder et al U.S. Pat. No. 3,957,055 and in Long U.S. Pat. No. 3,867,945 wherein a plastic catheter has an exposed opening at the end thereof to permit the withdrawal of specimens therethrough. No means is provided in this type of catheter to prevent contamination of the sampling catheter as it is inserted through or withdrawn from the patient's orifice.
In another device shown in Kohl U.S. Pat. No. 3,796,221, a pipette having an open-ended tube is employed to remove specimens from various internal locations. Although the pipette is inserted through a sheath, the open end of the sheath itself may contaminate the end of the pipette tube as the tube is moved therethrough.
Results of experiments employing a suction catheter with an inner telescoping catheter are reported in Cattaneo et al., "Selective Sputum Cultures", Journal of Thoracic and Cardiovascular Surgery 69 (January 1975): 152-159. The outer catheter has a sealing valve mechanism to minimize contamination of its bore during passage through the nose and pharynx. The valve sealing the distal opening was tripped as the inner catheter was advanced to an exposed position. However, as the inner catheter came through the side of the outer catheter, rather than through the end, the patient's airway was further obstructed resulting in the patient having difficulty respirating.
Khoury, British patent application number 35642/76, filed Aug. 26, 1976, discloses an outer catheter encasing a slidable tubular member which defines a passage through which the inner catheter travels. The slidable member provides means for spacing the passage of the inner catheter away from the inner wall of the outer catheter. The slide-receiving passage is closed by a thin membrane which prevents the inner catheter from becoming contaminated until the membrane is broken by the inner catheter itself, this occurring when the outer catheter is in a position to obtain the desired sample.